Thanks for the suggestions! I see that you are not alone. Other people have filed GitHub issues with similar suggestions. I don't know when I'll have time to work on them, but are links if you'd like to follow the issues:

Add option to tab context-menu:
https://github.com/cpeterso/open-page-in-private-window/issues/9

Add option to hide "Open page in private window" entry in page context-menu:
https://github.com/cpeterso/open-page-in-private-window/issues/11